Forward capturer_id between DesktopFrame and its implementations

This is a trivial change to forward capturer id from various DesktopFrame
related implementations.

BUG=chromium:679523, chromium:650926

Review-Url: https://codereview.webrtc.org/2851513003
Cr-Original-Commit-Position: refs/heads/master@{#17918}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 403267434950154c2c1bdaa53ab33ff622f0b91c
3 files changed